So-called “cell towers” have become ubiquitous in urban, suburban and rural areas in the United States and around the world. While there is a high and growing demand for cellular telephone and other wireless communication services, many people object to the appearance of conventional cell towers and do not want such towers installed in their neighborhoods or areas where the view is important. Thus, wireless service providers are faced with a dilemma: they must install additional cell sites if they wish to improve and expand their wireless coverage and their range of wireless services to satisfy customer demand; but they are often faced with strong public objection, unwillingness of building and land owners to lease the required space, and local zoning restrictions against erecting additional cell towers in the areas where they are needed to satisfy the local demand for wireless service.
Such “cell towers” are also known as “cell sites”, because some cell sites do not involve a tower at all, but rather merely comprise antennas mounted on an existing building or other structure and the associated electronic equipment housed in the structure or in a separate shelter, cabinet or enclosure. If no suitably located, and sufficiently tall, existing structure is available, then a tower must be erected to carry the necessary antennas, and a shelter, cabinet or enclosure must be provided to house the required equipment, shelter it from the elements and protect it from tampering. Typical types of towers include a lattice tower having zig-zag truss members tying together vertical corner members, a monopole tower in the form of a single cylindrical hollow pole, a guyed tower that may have a lattice construction or a monopole construction plus several guy wires extending away from the tower and anchored into the ground so as to stabilize and reinforce the tower, and various “stealth” or concealed towers that may have specialized construction and exterior camouflage finishing so as to try to hide or blend the tower into the existing surrounding urban or rural landscape. The equipment enclosure is typically in the form of a pre-fabricated steel cabinet, shelter, shed or building in which the necessary equipment is housed. Such an equipment enclosure is typically erected or placed on a concrete pad or other foundation adjacent to the foot of the tower.
The base transmitter station and other electronic equipment required for such a cell site may include electronic transmitters and receivers or transceivers, amplifiers, digital signal processors, control electronics, a GPS receiver and processor, primary and backup electrical power sources, and computer hardware and software for call handling and hand-off, channel allocation, bandwidth management, etc. as well as a backhaul communication cable connection to a remotely located mobile telephone switching office or mobile switching center for overseeing and controlling the call handling, channel allocation, frequency reassignment, etc. among several cell sites. The backhaul connection may be via a high capacity cable, e.g. in urban and suburban areas, or via a microwave link through one or more microwave antennas also mounted on the tower. The electrical power equipment typically includes a backup battery bank, a transformer and a connection to the power grid or an off-grid power supply such as a generator, solar panel array, wind turbine or fuel cell power source. If the equipment shelter is completely weather-tight and climate controlled (requiring additional heating, ventilating and air-condition equipment), then the electronics equipment to be housed in the shelter can be of the indoor type. On the other hand, often it is necessary to use outdoor certified equipment packages that provide all the necessary equipment, sheltering and climate control in a self-contained ready-to-deploy unit. However, such outdoor certified equipment packages come at a much higher cost, approximately double, compared to the cost of indoor type equipment.
The cell tower may also host other wireless communication and broadcast facilities including antennas and associated electronics equipment for radio broadcast, television broadcast, RF communication e.g. for walkie-talkie, mobile radio, and government frequency communication, as well as microwave communication and repeater links. Throughout the present disclosure, the term wireless communication is used broadly and encompasses all forms of wireless transmission and/or reception of any type of communication signal including voice, audio, video, data, location and locating signals, etc. The types of antennas carried by such cell towers may include omnidirectional antennas, sectoral antennas, surface wave antennas, micro strip antennas, array antennas, parabolic reflector antennas, dish antennas, and all other types of antennas for wireless communication.
The conventional cell sites suffer various problems, for example as follows. The ever increasing number of cellular telephones and other mobile wireless devices communicating via cellular networks is overburdening the available capacity of the existing cell cites. Namely, each cell site has a limited number of channels available and can thus handle only a limited number of simultaneous calls or communications, and each channel has a limited bandwidth i.e. a limited rate of data transfer. More cell phone and mobile wireless device users in a given area thus require more available channels, and the modern wireless devices transmitting audio, video, internet information and other data have a much higher demand for bandwidth than simple voice calls on cellular telephones. As a result, cellular service providers must erect a rapidly growing number of additional cell sites with smaller cellular coverage areas for each site, to provide a higher area density of available cell channels and bandwidth. For example, so-called “offload sites” on smaller towers are being erected to provide buffering and handle excess call volume shifted from larger primary sites on higher towers. These offload sites must have their antennas within a line of sight to a larger primary tower or between two larger primary towers for which they are providing offload or buffering service. Thus, it is becoming necessary to locate cell sites more closely together in urban and suburban areas to provide the required number of channels and the required bandwidth for each cell site's coverage area. As a result, cellular service providers need locations in existing urban and suburban landscapes where a new cell site may be installed. This becomes problematic for several reasons.
Most conventional cell towers are generally regarded as visually unattractive because they clutter or interrupt the existing skyline with unfamiliar or harsh-looking mechanical structures. Many people thus object to having a cell tower erected within their viewing area around their home or business, although these people may also demand improved cellular service coverage. Also, some building codes, zoning ordinances and other local ordinances prohibit the erection of such a tower or any structure that does not blend-in or conform to existing or specified architectural styles and appearances. In order to provide the demanded cellular coverage in such areas, cellular service providers have sometimes camouflaged or concealed cell towers, so called stealth towers, for example to look like one of the existing surrounding palm trees, pine trees, utility poles, or existing architectural structures such as a church steeple or other tower. However, such camouflage or concealment efforts give rise to significant additional costs in the design and installation of the cell tower, as well as additional legal costs in obtaining the necessary local zoning and building permit approval. The process of obtaining community acceptance as well as local zoning or building permit approval also adds significant time delay to the planning and installation of a new cell site. Another approach at concealing a new cell site has been to mount the cellular antennas on an existing building or other structure and install the associated equipment in a room in the existing building or in a separate enclosure on the roof thereof. However, such installations on an existing building often require re-engineering and structural modifications of the existing building to support the added load of the cellular communication facilities and to achieve a stealthy concealment thereof without blocking the wireless transmission and reception of the antennas. Also, the antennas and equipment must remain accessible for maintenance, replacement and repair, usually on a continuous 24/7 basis. Therefore, the cellular service provider must have access to the existing building or at least the areas thereof housing the equipment and allowing access to the rooftop or other location of the antennas. That causes potential problems for the building owner, and also gives rise to liability issues if the installed facilities or any maintenance access cause damage (e.g. a leaking roof) to the existing building.
Even in rural areas where free-standing cell towers are more common than cell sites installed in existing buildings, typical cell towers are still considered unattractive. Because cell towers are generally located relatively close to populated or well-traveled areas (e.g. along a highway) even in rural areas, a typical cell tower may be objectionable because it mars the otherwise pristine natural beauty of the surrounding rural landscape. On the other hand, a tower in the style of a fire watch tower, an observation tower, a silo, a clock tower or a steeple may not be objectionable in such locations, because such towers are more familiar within the rural landscape.
In addition to an unattractive appearance, conventional cell towers suffer a significant problem of icing during the winter in northern climes. Namely, atmospheric moisture in the form of rain, snow, fog, mist or even just high humidity tends to condense and then freeze on the metal truss members of lattice type towers. Ice can also accumulate on the antennas themselves, and the additional ice load must be taken into account in the structural design of the tower, the antennas and the antenna mounts. Furthermore, when the tower is subjected to any wind load bending or swaying, or the metal warms slightly due to changed weather conditions, then the accumulated ice breaks off and falls down from the tower truss members. The falling ice is a significant hazard to any persons and equipment in the area at the base of the tower. Because this falling ice has been known to damage equipment shelters, it is therefore necessary to build the equipment shelters stronger to resist the icefall damage and protect the equipment within. Occasionally, cellular equipment shelters and the equipment housed therein are also damaged by gunshots fired at the cellular facility. Thus, it has become known to fabricate an equipment shelter in the manner of a cast concrete bunker to provide icefall and ballistic protection. Such a concrete bunker is extremely heavy, and requires specialized heavy lift crane equipment or heavy lift helicopters for placement on site.
In a separate field completely unrelated to the above discussed field of wireless communication via cell sites, namely in the field of long distance transportation of goods, it has become the internationally accepted standard to transport various and diverse goods packaged within standardized steel shipping containers as freight or cargo on ships, trucks and railway trains (and even in aircraft). A standardized system has been developed, so that such a standardized shipping container can easily and efficiently be loaded, handled, transferred between, received in or on, and transported by such ships, trucks and trains that have been adapted according to the standards. In view of the different modes of transport, such containers are also known as intermodal shipping containers. Such shipping containers are available in standardized sizes having lengths of 10 feet, 20 feet, 40 feet, 45 feet, 48 feet and 53 feet, widths of 8 feet and 8 feet 6 inches on the outside, and heights of 8 feet 6 inches and 9 feet 6 inches. A standardized shipping container typically has a corrugated steel ceiling, floor, longitudinal side walls, and front end wall, as well as outwardly swinging double loading doors on the back or rear end. A flat steel or wooden load floor may be provided inside the container. The structure is welded together to provide a structurally strong and weather-tight enclosed container. All eight corners are provided with so-called twist-lock points that represent load bearing and load transfer points as well as securing or fastening points at which containers may be coupled, engaged, lifted, or stacked on each other in a secured and load transmitting manner. These are also the points at which a container is coupled on a flatbed truck or tractor truck, a railway train bed, or a ship cargo hold. The containers are longitudinally strong to withstand the arising bending loads of the container itself and the cargo load therein when the container is lifted by lifting points at the ends thereof or at provided fork lift slots. In this regard, the two longitudinally extending edges along the floor of the container are reinforced by continuous steel C-channel beams, and the two longitudinally extending edges along the ceiling of the container are reinforced by continuous steel square-sectional beams. Also, the containers are sufficiently strong in the height direction, against crushing or buckling, so that several containers can be stacked one on top of another. In this regard, the four vertical edges of the container are reinforced with steel posts at all four corners.
A given shipping container is often used several times for bi-directional shipping of different goods back and forth between two locations, or for sequential shipping of different goods from point A to point B, then from point B to point C, then from point C to point D, and then perhaps back to point A. However, when the balance of trade, or especially the balance of shipments into and out of a given location is unbalanced and involves a greater number of inbound shipments than outbound shipments, this results in stockpiling of empty shipping containers at such a location. Because new shipping containers can be purchased quite cheaply in some countries having a high net exporting balance of trade, such as China, it is cheaper and simpler to purchase a new shipping container for import shipping further cargo, rather than return-shipping an empty container back to such a country (e.g. China) for re-use. As a result, empty used shipping containers are being stockpiled in some locations in the United States, and are available cheaply as scrap steel, or for recycling, upcycling, reuse or refabrication.
It is becoming known to use such steel shipping containers as core structures for various buildings, such as storage sheds, mobile restaurants, camping cottages, and even as apartments, hotels and individual private residence homes. To modify or re-fabricate a shipping container for such uses, it is known to cut openings for doors or windows in the steel walls of the shipping container and to provide suitable interior finishes, fittings and furnishings for the intended use. Moreover, such applications make use of the inherent structural strength of the shipping container for carrying bending loads along the horizontal lengthwise axis thereof, and vertical compressive loads along the four vertical edges thereof. Because of the standardized sizes of the available shipping containers, clusters of such shipping containers can be grouped or arranged modularly to form a repetitive housing structure such as an apartment complex, or can be modularly interconnected to construct a larger building having an overall configuration made up of several interconnected shipping containers. In view of such building structure applications of shipping containers, these standardized containers are also known as Intermodal Steel Building Units (ISBU) or ISBU shipping containers.